In various past inking units, in order to achieve zone-wise dispensing of the film of ink produced on the duct roller, the individual ink dispensing or metering elements are so adjusted in respect of their distance from the duct roller as to form a metering gap which allows the required amount of ink to flow therethrough. Depending on the size of the gap, very high hydrodynamic pressure forces may occur between the ink metering elements and the duct roller. In zones with the smallest ink flow these pressure forces are of a value many powers of ten higher than zones with a considerably larger ink flow. Each additional adjustment of the ink metering elements therefore results in a different loading and deflection of the duct roller over the entire machine width so that accurate adjustment of the individual ink metering elements is time-consuming and difficult as they are repeatedly adjusted with respect to one another.
One known inking unit of this kind is disclosed in German Offenlegungsschrift No. 27 33 845, wherein a retaining block carries the ink metering elements in a duct extending over the entire printing machine width and has a stop or abutment which abuts the duct roller when the block is pressed against the duct roller. The stop abutment surfaces are of a curvature corresponding to the duct roller. This known system is intended to provide direct adjustment of the block and of the ink metering elements with respect to the duct roller and obviate any effects of the mounting of the duct roller and of the duct in the machine frame. However, deflection of the duct roller cannot be detected and compensated for with this system.